Coated abrasive article

ABSTRACT

An improvement in coated abrasive articles for wet or dry grinding comprising a finished fabric support, an elastic impermeable intermediate layer, a layer of abrasive particles and a resin binder for the abrasive particles, wherein the intermediate layer is a cured mixture comprising: A. EPOXIDE RESIN BASED ON 4,4&#39;&#39;-DIHYDROXY-DIPHENYL-2,2-PROPANE, SUBSEQUENTLY CALLED Bisphenol A; b. an epoxide resin based on Bisphenol A internally plasticized by reaction with castor oil; C. CARBAMIC ACID ALKYL ESTERS; AND D. CURING AGENTS.

Inventors Hermann Singer Hamburg; Johann Kuhr, l-larksheide; Hermann Delius, Ahrensburg; Dietmar Wunderllclh, Hamburg, all of Germany Appl. No. 768,828 Filed Oct. 18, 1968 Patented Oct. 26, 1971 Assignee Reicllhold-Albert-Chemie Aktiengesellschaft Hamburg, Germany Priorities May 31, 1968 Switzerland 841 1/68; Oct. 25, 1967, Germany, No. R 36214; Oct. 25, 1967, Germany, No. R 36215; Oct. 25, 1967, Germany, N0..R 36217; Oct. 25, 1967, Germany, No. R 47216; Oct. 25, 1967, Germany, No. R 47 217; Oct. 25, 1967, Germany, No. R 47218 COATED ABRASIVE ARTlClLlE 12 Claims, 11 Drawing Figs.

U.S. Cl 51/295, 51/297, 51/298 Int. Cl 1324b 1/00,

50 Field ol sefilt'cll 5172'9T'" [56] Relerenccs Cited UNITED STATES PATENTS 3,316,072 4/1967 Voss 51/295 3,466,814 9/1969 Singeretal. 3,487,593 l/1970 Vinard Primary Examiner-Donald J. Arnold Att0rney Krafft & Wells PAIENTEnnm 2s IQTI SHEET 1 BF 3 mm m INVENTORS I ermann Singer Johann K L'ihl" Hermann Del/us D/efmar Wunderlr'ch ATTORNEYS GU26)?! 3,615,303 PATENTED SHEET 2 BF 3 llllrn LLJ 1 1 1 1 r I 1 I 1 I 7 INVENTORS Hermann Singer Johann I'd/hr Hermann Del/us Dl'efrnar Minder/[ch y W if mm A TORNEYS PATENIEUUB 2 I9?! 3, 6 l 5 3 O3 sum 3 OF 3 mvemoas Hermann inger" Johan/m Kz'ihr' Hermann De/ius D/efm ar" Wunder/ich B Wi l? Z11 ATTORNE Y6 comma AnaAsrva ARTICLE CROSS-REFERENCES TO RELATED APPLICATIONS BACKGROUND OF THE INVENTION The field of the invention is abrading and abrasive tool compositions having synthetic resins therein. The invention is particularly concerned with resin coated abrasive articles.

The state of the prior art may be ascertained by reference to the Kirk-Othmer "Encyclopedia of Chemical the 2nd Ed., Vol. 1 (1963), pages 22-44, and particularly pages 29-31 under the section entitled Abrasives"; Vol. 4 (1964), pages 69 and 70, under the section entitled Carbamic Acid"; and Vol. 8 (1965), pages 294-312, under the section entitled Epoxy Resins. The state of the prior art may also be discovered by referring to West German Pat. specification No. 1,226,451 and U.S. Pat. No. 3,466,814.

For the use of phenolic resin-bonded abrasive fabrics, support materials with different finishes are used depending on whether the abrasive fabric is to be employed for dry grinding or for wet grinding.

The comments which follow relate to abrasive fabrics which in grinding technology are used for dry grinding and wet grinding respectively.

The finishes of the grey fabrics used as supports for the abrasive fabrics, especially cotton fabrics, but also fabrics based on regenerated cellulose, polyamide, polyacrylonitrile and polyester fibers as well as mixtures thereof, is, for dry grinding, applied by impregnation and/or coating of these fabrics with hide glue, starch (starch derivatives) or dextrin finishes, the partial conjoint use of aqueous synthetic resin dispersion for the process of finishing the support fabric is also possible.

The grey fabrics intended as supports for wet grinding are finished by impregnating and/or coating these fabrics with ureaformaldehyde precondensates, polyvinyl acetate dispersions, copolymeric acrylate dispersions, aqueous phenolic resins or plastic polymers. These compounds can be used by themselves or in combination.

In order to avoid excessive penetration into the support fabric of the resin binder used for binding the abrasive particles, the surface of the support fabric which faces the abrasive particles is provided with impregnating and/or coating compositions of various constitutions, the task of which it is to effect a good bond between the finished support fabric and the abrasive particle binder.

It is also possible to provide the prefinished abrasive fabric with these impregnating and/or compositions by means of a full bath impregnation. Admittedly the active intermediate layer is then applied to both sides.

The following have hitherto been used and/or proposed for this purpose: pure and modified phenolic resins, especially aqueous phenolresols; combinations of phenolic resins and polyamides; combinations of phenolic resins and plastic dispersions; combinations of epoxide resins with polyamidoamines; mixtures of epoxide resins based on Bisphenol and diglycidyl ethers of polyglycols in conjunction with usual curing agents.

When using these known intermediate coatings significant disadvantages arise, namely, when using phenolic resins or phenolic resin-polyamide combinations and combinations of phenolic resins and plastic dispersions there is the danger of embrittlement of the support fabric. The resulting adhesive action in the coarser particle range is inadequate and the tearstarting resistance of the fabric is considerably reduced.

When using combinations of epoxide resins with polyamidoamines the heat resistance is poor. As a result of the peculiar nature of this coating, the wettability with aqueous phenolic resin binders is rendered extremely difficult, especially if a thin application is to be made.

Even when using only small proportions of polydioldiglycidyl ethers in the mixture with epoxide resins based on Bisphenol in conjunction with usual curing agents, coatings are obtained which in respect of heat resistance, adhesion promotion, mechanical properties and moisture resistance are not fully satisfactory in all cases, especially when using granular abrasives in the coarser particle size range.

SUMMARY OF THE INVENTION The present invention relates to abrasive fabrics for dry grinding or wet grinding consisting of a finished fabric support, an elastic impermeable intermediate layer and a resin binder layer for the abrasive particles, characterized by the use of a cured mixture consisting of the combination of:

a. epoxide resin based on 4,4-dihydroxy-diphenyl-2,2-

propane, subsequently called Bisphenol A;

b. an epoxide resin based on Biisphenol A internally plasticized by reaction with castor oil;

c. carbamic acid alkyl esters; and

d. curing agents as the intermediate layer.

According to the present invention abrasive fabrics are obtained of which the effectiveness in respect of grinding technology is in various respects superior, also in the coarser particle size range, to abrasive fabrics, which are manufactured according to the previous state of the art. The advance over the prior art achieved is attributable to the fact that the composition of the intermediate layer used in accordance with the invention produces excellent adhesion promotion between the support fabric and the resin binder. The strength and flexibility of the fabric are not impaired. Compared to the previously used and proposed intermediate layer systems, the following special advantages are, inter alia, to be observed: the use as an intermediate layer of the combination which has been characterized admittedly results in a distinct plasticization of the intermediate layer without, however, thereby impairing the heat resistance and mechanical strength of the total coating system, so that no premature failure of the abrasive fabric occurs from heavy stresses in a grinding process.

BRIEF DESCRIPTION OF THE DRAWINGS The invention may be best described by reference to the drawing wherein:

FIG. 1 is a detailed sectional view showing the construction of the phenolic resin bonded abrasive fabrics according to the invention;

FIG. 2 is a sectional view of the abrasive particle support on prefinished fabrics;

FIG. 3 is a sectional view showing the abrasive particle support of prefinished fabric and the upper effective intermediate layer 2 and the lower impregnating layer 2 of the same material;

FIG. 4 is a perspective view partly in section which shows an abrasive fabric having the intermediate layer according to the invention;

FIG. 5 is a perspective view partly in section showing an abrasive fabric which has been manufactured from the support according to FIG. 3;

FIG. 6 shows in cross section a component of the fabric web for supporting abrasive articles as shown in FIGS. 1 to 5;

FIG. 7 shows in cross section the construction of abrasive fabric webs manufactured according to the invention having an abrasive particle deposit 3 with 11 representing the cotton fabric abrasive particle support impregnated with the novel fabric finish of the present invention;

FIG. 8 shows in cross section the abrasive particle support of the fabric web finished according to the present invention;

FIG. 9 shows in cross section the construction of a support fabric web consisting of the fabric impregnated according to the invention, the reverse side smoothing coat according to the invention which contains fillers and the intermediate fillerfree layer according to the invention on the front side;

FIG. 10 is a perspective representation of the sectional appearance shown in FIG. 1 wherein the article is constructed in accordance with the fabric finish shown in FIG. 9; and

FIG. 11 is a perspective representation of an abrasive fabric for which the fabric has the finish represented as shown in FIG. 8.

FIG. I shows the construction of phenolic resin bonded abrasive fabrics according to the invention, having a deposit 3 of abrasive particles with 1 representing the abrasive particle support of prefinished fabric. The abrasive particle binder 6 consisting of the phenolic resin based binder 4 and the phenolic resin covering binder is shown clearly. The intermediate layer according to the invention is marked by the number 2. The following may be used as the deposit 3 of abrasive particles: aluminum oxide abrasives, corundum and silicon carbide in various classes and grades as used in the abrasive industry.

FIG. 2 shows the abrasive particle support on prefinished fabric and intermediate layer 2 with a composition according to the invention. A twill fabric having a grey fabric weight of 270 grams per square meter is suitable as the abrasive particle support.

FIG. 3 shows the abrasive particle support on prefinished fabric and the upper effective intermediate layer 2 and a lower impregnating layer 2 of the same material which is necessarily obtained at the same time when using full bath impregnation. The lower layer 2 does not have to fulfill the purpose according to the invention in this instance. This lower layer 2 solely contributes advantageously to a further stiffening and increased strength of the abrasive support.

FIG. 4 again makes clear an abrasive fabric having the intermediate layer according to the invention.

FIG. 5 shows an abrasive fabric which has been manufactured from a support according to FIG. 3.

FIG. 6 shows at A the core-sized and finished yarn A without interfacial layer and the finished weft B. This is a constituent of FIGS. l-5 with the fabric web for supporting abrasive particles, shown in FIG. 1.

FIG. 7 shows the construction of abrasive fabric webs manufactured according to the invention having an abrasive particle deposit 3, with I representing the cotton fabric abrasive particle support impregnated with the novel fabric finish described in the following specific embodiments. The abrasive particle binder 6 consisting of the primer binder 4 and the covering binder 5 are clearly shown. Silicon carbide in the particle size gradations usual in the abrasive industry can, for example, be used as the abrasive particle deposit 3. Furthermore, the filler-free composition according to the invention which is additionally applied to the intermediate layer 2 is shown. This intermediate layer 2 significantly improves the properties of the abrasive fabric webs over those of the prior art, as the result of these tough and elastic properties, they form a suitable foundation from a flexible support web to the hard synthetic binder of abrasive particle deposit. Coating 7 shows the novel composition, containing fillers, as a reverse side coating of the support fabric web impregnated according to the invention. The composition used according to the invention, as an applied filler-free coating, is indicated with the number 2.

FIG. 8 shows the abrasive particle support of a fabric web finished according to the invention with the new compositions as the fabric finish I and the applied reverse side coating, containing fillers 7. In this embodiment the abrasive particles are supplied without the intermediate layer 2.

FIG. 9 shows the construction of a support fabric web consisting of the fabric 1 impregnated according to the invention,

the reverse side smoothing coating 7 according to the invention containing fillers, and the intermediate filler-free layer according to the invention 2 on the front side.

DESCRIPTION OE THE PREFERRED EMBODIMENTS The following epoxy resins, based on Bisphenol A are usable: liquid and solid epoxy resins which are produced by the reaction of Bisphenol A with epichlorohydrin, respectively glyceroI-dichlorohydrin in an alkaline medium.

The epoxy resins based on Bisphenol A have epoxy equivalent weights which lie in the range between 180 and 500. The viscosities of the liquid resins are between about 10,000 add 60,000 cP at 25 C. Solid resins with melting points below about 75 C. (checked by the Durran method) are also suitable. Epoxy resins based on Bisphenol A are also suitable in the form of mixtures of liquid epoxy resins with socalled reactive diluents which are monoepoxide or diepoxide compounds such as, for example, butyl glycidyl ether, phenol glycidyl ether, cresyl glycidyl ether and styrene oxide, and vinylcyclohexene dioxide.

The viscosities of these mixtures lie between 400 and 5,000 cP.

Epoxide resins based on Bisphenol A which are internally plasticized by reaction with castor oil comprise those resins which are manufactured by reaction of Bisphenol A diglycidyl ether with castor oil in the molar ratio of 1:0.25 to l:0.3, such as, for example, an internally plasticized epoxide resin having an epoxide equivalent of 450-550, and a viscosity of 40,000-50,000 cP at 25 C. The reaction between the Bisphenol A diglycidyl ether and the castor oil is carried out in the presence of Lewis acids, such as tin tetrachloride, boron trifluoride and its addition compounds, for example, to acetic acid, ethyl ether, phenol, cresol and piperidine. The reaction products of epoxide resins with castor oil still contain epoxide groups so that they can be cured with conventional curing agents.

As epoxide resin based on Bisphenol A, unmodified liquid resins having an epoxide equivalent of between 170 and 280 are preferentially usable.

As epoxide resins based on Bisphenol A which are internally plasticized by reaction with castor oil, reaction products of epoxide liquid resins having an epoxide equivalent of between 170 and 280 with castor oil are preferentially usable. Herein the reaction products have epoxide equivalents of between 450 and 700 and viscosities between 40,000 and l00,000 cP.

All parts relate to parts by weight:

Usable mixing ratios of the resin types characterized under (a) and (b) of the Abstract lie between 10 parts by weight of epoxide resin based on Bisphenol A and parts by weight of epoxide resin based on Bisphenol A which is internally plasticized by reaction with castor oil, and

90 parts by weight of epoxide resin based on Bisphenol A. and

10 parts by weight of epoxide resin based on Bisphenol A which has been internally plasticized by reaction with castor oil.

Preferred mixing ratios lie within the limits of 80 parts by weight of epoxide resin based on Bisphenol A, and

20 parts by weight of epoxide resin based on Bisphenol A which has been internally plasticized by reaction with castor oil, and

parts by weight of epoxide resin based on Bisphenol A,

and

five parts by weight of epoxide resin based on Bisphenol A which has been internally plasticized by reaction with castor oilv Liquid resins can be used in the form of solvent-free mixtures as well as in the form of solutions. Solid resins on the other hand are always processed in the form of a solution.

As carbamic acid alkyl esters, it is possible to use the methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl or dodecyl alcohols, preferably the ethyl and/or butyl alcohol, as a constituent of the ester. These carbamic acid alkyl esters may be added in amounts of about 0.5 to 80 percent by weight relative to the epoxide resin component. The preferred range for the addition is, in the case ofa predominant proportion of unplasticized epoxide resin, 1 to 40 percent by weight, and in the case of a predominant proportion of plasticized epoxide resin 0.5 to percent by weight.

Usable mixing ratios of the resin types mentioned under (a), (b) and (c) of the Abstract lie between 10 parts by weight of epoxide resin based on Bisphenol A and 90 parts by weight of epoxide resin based on Bisphenol A which is internally plasticized by reaction with castor oil and 0.5 parts by weight of carbamic acid alkyl ester, and 90 parts by weight of epoxide resin based on Bisphenol A, 10 parts by weight of epoxide resin based on Bisphenol A which is internally plasticized by reaction with castor oil and 80 parts by weight of carbamic acid alkyl ester.

Preferred mixing ratios lie within the limits of:

80 parts by weight of epoxide resin based on Bisphenol A; and

parts by weight of epoxide resin based on Bisphenol A which is internally plasticized by reaction with castor oil; and

0.5 parts by weight of carbamic acid alkyl ester; and

95 parts by weight of epoxide resin based on Bisphenol A; and

5 parts by weight of epoxide resin based on Bisphenol A which is internally plasticized by reaction with castor oil; and

40 parts by weight of carbamic acid alkyl ester.

Liquid resins can be used both in the form of solvent-free mixtures and also in the form of solutions. Solid resins on the other hand are always processed in the form ofa solution.

Quite generally all substances which are suitable for curing epoxide resins, such as for example, aliphatic polyamines, aromatic polyamines and acid anhydrides, are usable as curing agents in the use according to the invention.

Particularly suitable curing substances are aromatic polyamines such as, for example, metaphenylenediamine, 4,4-diaminodiphenylmethane, and diaminodiphenylsulphone. The use of these substances makes it possible, by impregnation or coating and subsequent drying in the usual manner, to obtain a physically dry nontacky intermediate layer which, viewed chemically, is not yet cured. This makes possible a subsequent reaction or joint cure with the subsequently applied phenolic resin binder and/or other binders based on resin, resulting in particularly good adhesion between the binder and the support fabric.

The curing agents are used in nearly stechometrical amounts, that means amounts of l0 percent more or less of the theory are also usable. Under stechometrical amounts is understood that per one equivalent of the epoxide resin, one H=active=equivalont molecular Weight of the amine number of the active hydrogen atoms ofthe amine is used.

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The following preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the specification and claims in any way whatsoever.

The intermediate layer according to the invention is applied to suitable support materials. Certain support materials such as suitable cotton and/or rayon fabrics and/or mixed fabrics are preferred. Examples of the intermediate layer composition in accordance with the invention follow.

EXAMPLE I 170 parts by weight of epoxide resin based on bisphenol A (liquid resin of medium viscosity, epoxide equivalent 185-195, total chlorine content maximally 0.3, viscosity l0,00015,000 c? at C.):

parts by weight of epoxide resin based on Bisphenol A which is internally plasticized by reaction with castor oil (plasticized liquid resin, epoxide equivalent 450-550, total chlorine content maximally 0.2, viscosity 40,000-50,000 cl at 25 C.

Three parts by weight of carbamic acid ethyl ester and 27.5 parts by weight of metaphenylenediamine are well mixed and subsequently applied as an intermediate coating, on the particle side of the textile-finished support material.

EXAMPLE 2 190 parts by weight of epoxide resin based on Bisphenol A (as in example 1);

10 parts by weight of epoxide resin based on Bisphenol A which is internally plasticized by reaction with castor oil (as in example 1);

10 parts by weight of carbamic acid ethyl ester;

54 parts by weight of4,4-diaminodiphenyl-methane; and

20 parts by weight of solvent (xylene-methyl isobutyl ketone :20) viscosity (Gardner): 'W-X, are thoroughly mixed and subsequently applied as an intermediate coating on the particle side of the finished fabric.

EXAMPLE 3 180 parts by weight of epoxide resin based on Bisphenol A (as in example 1);

20 parts by weight of epoxide resin based on Bisphenol A which is internally plasticized by reaction with castor oil (as in example 1);

20 parts by weight of carbamic acid ethyl ester;

67 parts by weight ofdiaminodiphenylsulphone; and

26 parts by weight of solvent (xylene-methyl isobutyl ketone 80:20) viscosity (Gardner): W-X, are well mixed and applied as an intermediate layer to the particle side of the finished fabric.

Examples for the manufacture of phenolic resin-bonded abrasive fabrics using, according to the invention, the intermediate layer composition which may be disposed on the fabric either on the punch side or on the particle side or in the fabric, preferably on the particle side on the fabric.

The starting fabric is a finished grey fabric for abrasives in twill construction, having a grey fabric weight of -400 g./m. preferably 200 g./m. The side of the fabric which faces the deposit of abrasive particles is coated with an intermediate layer composition described in accordance with the invention and in accordance with Examples 1 to 3, at an order ofmagnitude of 20 g. of solids per square meter.

it is also possible to achieve the application of the active intermediate layer by a full bath impregnation of the prefinished fabric for abrasives. When using intermediate layer compositions which contain solvent, the material is dried at room temperature or a slightly elevated temperature. Thereafter a liquid phenol-formaldehyde condensation product having a viscosity of 8,000 to 10,000 c? at 20 C. with a B-time (cure time until the phenolic resin changes to the so-called B-state) of about 12 minutes at C. is applied in an amount of 120 g./m. Normal corundum powder is scattered into this phenolic resin binder layer while it is still moist.

The precure of the base binder is now taken beyond the B- point to the stage that the abrasive particle is well fixed to the support surface so that on application of the covering binder it can no longer be broken away from the base binder and can also no longer change its position.

A liquid phenol-formaldehyde condensation product having a viscosity of 1,000 cP at 20 C. is used in the pure form as a covering binder. Instead of this binder, it is also possible to use a mixture of 60 parts by weight of liquid phenol-formaldehyde condensation product and 40 parts by weight of inorganic fillers.

This binder is applied by the roller application process in an amount of 250 to 300 g./m. The cure is effected over the course of 6 hours using a curve for the temperature course which has been empirically established to be the optimum.

After the curing process, the abrasive article which has necessarily been dried out during the cure, is returned to its hygroscopic equilibrium under normal climatic conditions by moistening it with steam.

These abrasive fabrics which have been provided with the intermediate layer composition of the invention according to Examples 1 to 3 are distinguished, in comparison to the abrasive fabrics manufactured with usual intermediate layers, by the advantages which have already been mentioned in the description.

The following test procedure serves to show the advance over the prior art achieved by the invention:

Two at a time of identical abrasive fabrics were coated with synthetic resin, pressed together mirror-fashion andcured in this state, and the peel strength according to DIN (German lndustrial Standard) 53,530 was tested.

A pure cotton fabric which was finished in the manner usual for the manufacture of a fully synthetic resin-bonded abrasive cloth in the abrasive cloth industry served for the experiments. it had a weight per unit area of 325 g./m. and a construction of 32 warp ends per centimeter and 20 weft picks per centimeter.

Comparison 1 with the state of the art, German Pat.

specification No. 1,226,451 and U.S. Pat. No. 3,466,814

Two strips of fabric of dimensions x20 cm. were half coated with 50 g./m. in each case of a usual epoxide resin intermediate layer without carbamic acid ester. These epoxide resin coatings were lightly precured by lying for several hours at room temperature. Thereafter on fabric strip was coated on the epoxide resin layer with a binder based on phenol-formaldehyde which is usual in the abrasive industry. The coating weighed about 100 g./m."

An identical abrasive fabric not coated with phenol-formaldehyde was applied mirror-fashion (right-hand side onto righthand side) and a slight pressure was exerted on the two outer halves. This assembly was cured under pressure for 7 hours in a drying cabinet at temperatures increasing from 40 to 130 Comparison 2 using the intermediate layer according to the invention TEST The samples were stored for 3 days in a standard climate (65 percent relative atmospheric humidity and 20? C.), cut into double strips of width 1.5 cm. in line with the yarn in the warp direction, and the parts of the strip which had not been glued together were clamped in the upper and lower jaws of a tensile strength tester, system Schopper. The forces which were necessary to peel the two layers of fabric from one another were measured.

Comparison 1 (normal epoxide resin intermediate layer) 1.8 kp. Comparison 2 (epoxide resin intermediate layer according to the invention) 2.3 kp.

SUMMARIZING ASSESSMENT The test results showed that the use of the epoxide resin intermediate layer described in accordance with the invention effects a considerable increase in the strength of adhesion of the cured binder layer based on phenol-formaldehyde to the support fabric.

Since the abrasive particles are embedded in this binder layer, it can also be safely assumed that the use of the epoxide resin intermediate layer according to the invention can result in a significant increase in the strength of adhesion of the abrasive particles to the support. A direct test of the strength of adhesion of the abrasive particles to the support layers is not possible. The results are in line with experiences gained in the manufacture of the abrasive fabrics according to the invention.

In a particularly preferred embodiment of the invention, the abrasive fabric consists of fibers based on native and regenerated cellulose, preferably of the polynosic type, and of synthetic fibers such as, for example, polyamide, polyester or polyacrylonitrile fibers and their mixtures, which before application of the intermediate layer according to the invention are provided with a finish, this being characterized in that a fabric web for supporting abrasive particles is obtained in which:

a. the warp yarn is sized and finished and the size and finish are bonded in a firmly adhering manner without an interfacial layer; and

b. the warp yarn possesses a finish.

To the extent that the warp yarn and/or weft yarn of the support fabric consists of cotton, the fiber material must be freed of substances accompanying the growth of cotton, such as fat, waxes, pectins and the like, either in the unspun state, that is to say, in flock form, or in the spun state as a yarn before weaving.

The possible washing and rinsing processes for this are, for example, described in the textbook of Textile Chemistry of Hermann Rath, second edition, Springer Verlag 1963), pages 53 to 56. Essentially the fiber material in the aqueous medium is subjected to an alkaline treatment with a subsequent washing and rinsing process.

A particular embodiment of the fabric web for supporting abrasive particles is characterized in that the warp yarn is provided with a core size (core sizingsee in this context the Journal Adliflsion, (year 1961 No. 10, pages 505-512, and No. 11, pages 564-577, and No. 12, pages 617-622, in the article on Sizing Agents for the Textile lndustry of Erich P. Frieser).

In a further embodiment, the fabric web for supporting abrasive particles is characterized in that the finish present on the warp yarn and weft yarn has been applied by finishing with a finishing agent which contains an organic solvent or swelling agent which is emulsified in the aqueous medium and which is a swelling agent at temperatures of 1545 C. and a solvent at above 65 to 200 C. for the size present on the warp yarn.

A fabric web for supporting abrasive particles, manufactured in this way, has the great advantage that the finish of the abrasive fabric is bonded in a firmly adhering manner to the core-sized warp yarn and the weft yarn.

The manufacture of the present fabric web for supporting abrasive particles results in the advantage that large amounts of finishing agent do not have to be applied during finishing, since the warp yarn is already core-sized and these size constituents become a constituent of the finish as a result of their material composition. Furthermore, the novel arrangement in the fabric web for supporting the abrasive particles results in a high flexibility of the web.

The warp yarn and weft yarn of the fabric webfor supporting abrasive particles may consist of fibers or fiber combinations, with cotton being intended for use for a particle size range of (international standard), and below, and regenerated cellulose fibers, preferably polynosic fibers for abrasives in strip form, being intended for use for finer particle sizes. A mixture of the warp and weft yarns in the mixing ratio of 66 percent by weight of cotton and 33 percent by weight of rayon proves favorable in the coarse and fine particle size range and-a mixture of 45 percent by weight of cotton and 55 percent by weight pf rayon in the fine particle size range. The admixture of a synthetic fiber component of up to 45 percent by weight of cotton and rayon yarn is also advantageous for wet strength material, with possible synthetic fibers being those of the polyester, polyamide and polyacrylonitrile type.

The following can, for example, be used as a size for the warp yarn or preferably as a core size: degraded starch and starch derivatives, synthetic resins based on isocyanates, homopolymeric and/or copolymeric acrylic compounds (butyl acrylates and methyl acrylates), polyvinyl alcohol, polyvinyl acetate, acrylonitrile-butadiene-styrene copolymers in the form of solutions or dispersions and appropriate wetting agents, for example, napthalenesulphonates, acrylic derivatives or fatty alcohol polyglycol ethers, individually or in combination.

A preferred core size consists of:

30-50 parts by weight of corn starch, rice starch or potato starch which has been digested by acid degradation;

3-20 parts by weight of fatty alcohol polyglycol ether, preferably cocoanut fat alcohol having 5-12 molecules of ethylene oxide per fat molecule;

-50 parts by weight of copolymeric aqueous acrylate dispersion of 35 percent by weight of ethyl acrylate, 10 percent by weight of methacrylic acid, 40 percent by weight of methyl methacrylate and percent by weight of acrylamide; and

957-840 parts by weight of water.

Another preferred core size consists of:

l-25 parts by weight of a water-soluble copolymer and 30 percent by weight of acrylic acid and 70 percent by weight of butyl acrylate;

3-15 parts by weight of cocoanut fat alcohol polyglycol ether having 5-12 ethylene oxide groups per fat molecule;

10-80 parts by weight of copolymeric aqueous acrylate dispersion of 45 percent by weight of ethyl acrylate, 35 percent by weight of butyl acrylate, 10 percent by weight of vinyl acetate and 10 percent by weight of N- methylolacrylamide; and

986-870 parts by weight ofwater.

Possible finishes for the sized warp yarn and for the weft yarn are for example: animal hide glue and/or reactive and nonreactive copolymeric acrylate solutions or aqueous dispersions, polyisocyanates, polystyrene, N-methylol compounds of urea and its derivatives, aldehydes and its derivatives, sulphone compounds, phenol-formaldehyde-resol resins, polyvinyl alcohol, polyvinyl acetate and polyvinyl chloride in the form of dispersions and solutions, epoxide resins and polyester resins, as well as starch, starch derivatives and ethoxy adducts, with these containing emulsified in the aqueous medium, organic solvents or swelling agents which at temperatures of l5-45 C. are a swelling agent and above 65-200 C. are a solvent for the size present on the warp yarn, or for a 555 thereof. Emulsifiable organic solvents suitable for this purpose are, for example, toluene, toluene xylene, ethyl acetate, white spirit, trichlorethylene, perchlorethylene, and methylene chloride. Preferred finishes consist of:

10-100 parts by weight of animal hide glue (300 bl. gr. 100

80-30 parts by weight of copolymeric aqueous acrylate dispersion of 45 percent by weightpercent by weight of ethyl acrylate, 5-20 percent by weight of methacrylic acid, 0-25 percent by weight of acrylonitrile, 0-45 percent by weight of butyl acrylate and 5-15 percent by weight of N-methylolacrylamide;

5-10 parts by weight of cocoanut fat alcohol polyglycol ether having 5-12 molecules of ethylene oxide per molecule of fatty alcohol;

1-35 parts by weight of chlorinated hydrocarbons,

preferably methylene chloride; and

785-864 parts by weight of water, or of 50-150 parts by weight of an aqueous copolymeric acrylate dispersion of 45-20 percent by weight of ethyl acrylate, 5-25 percent by weight of methacrylic acid, 0-40 percent by weight of acrylonitrile, 0-45 percent by weight of butylacrylate and 5-15 percent by weight of N- methylolacrylamide;

3-20 parts by weight of water-soluble copolymer of 30 percent by weight of acrylic acid and 70 percent by weight of butyl acrylate;

5-40 parts by weight of dimethylolglyoxal-monourein;

1-5 parts by weight of magnesium chloride;

l-30 parts by weight of toluene; and

755-940 parts by weight of water.

The use of the preferred finishing agents results in the following specific advantages. The crosslinking acrylate dispersions, used as a constituent of the finish, possess good adhesive properties towards the subsequently to be applied intermediate layer compositions according to the invention, and furthermore, an embrittlement of the fabric is thereby avoided.

Furthermore, the fabric web for supporting abrasive particles may be provided with the same finish on both sides of the web, as is, for example, achieved by a clipping or impregnating process or by a spreading or doctorinig process carried out on both sides.

EXAMPLE 4 A warp yarn of count number 34 regenerated cellulose fiber (polynosic type) or a cotton fiber material which has before spinning, that is to say, in the block form, been boiled with alkali, washed and rinsed, is core-sized in a sizing trough using a formulation consisting of parts by weight of starch digested by acid degradation;

3 parts by weight of fatty alcohol polyglycol ether, cocoanut fat alcohol polyglycol ether having eight ethylene oxide groups per molecule; and

917 parts by weight of water and dried on a cylinder drying machine and subsequently woven with a weft yarn of count number 34, which is not sized, to give a .l-grey fabric for abrasives (twill fabric, warp 38.5 ends/cm, weft 26.5 picks/cm). The grey fabric for abrasives manufactured in this way is impregnated, without desizing, with a finish consisting of:

50 parts by weight of animal hide glue (300 bl. gr. mp.);

100 parts by weight of a copolymeric aqueous acrylate dispersion of 45 percent by weight of ethyl acrylate, 5 percent by weight of N-methylol-acrylamide and 50 percent by weight of vinyl acetate;

50 parts by weight of kaolin;

3 parts by weight of naphthalenesulphonate; and

797 parts by weight of water, and dried at 145 C. with simultaneous stretching and with a sideways contraction of about 1 1.5 percent, and set. The content of finish in the finished supports of type J for abrasive particles is 30 percent. The average weight per unit area is about 275 g./m. The finished fabric is coated on the particle side with a composition as described in example 1, and is processed to the finished abrasive fabric as described in the continuation of the examples.

EXAMPLE 5 5 parts by weight of water-soluble copolymer of +percent, by weight of acrylic acid and 70 percent by weight of' butyl acrylate; and 875 parts by weight of water; and subsequently dried in an air tunnel at C. and set. 10 percent of absolutely dry size are present on the warp yarn. After weaving (twill fabric, warp 34 ends/cm, weft 20.5

picks/cm.) with an unsized weft yarn of count number 27, the X-grey fabric for abrasives is, without desizing, immediately impregnated with a finishing solution consisting of:

120 parts by weight of reactive copolymer aqueous acrylate dispersion, 45 percent by weight of ethyl acrylate, 35 percent by weight of butyl acrylate, 10 percent by weight of vinyl acetate and 10 percent by weight of N- methylolacrylamide;

parts by weight of a copolymer of 30 percent by weight of acrylic acid and 70 percent by weight of butyl acrylate;

20 parts by weight of toluene;

60 parts by weight of kaolin;

20 parts by weight of dimethyloldihydroxy-ethyleneurea;

2 parts by weight of magnesium chloride; and

773 parts by weight of water and dried at 140 C. while stretching it, in the course of which the fabric contracts by l 1.5 percent in its width, and set. The content of finish in the finished support fabric of type X for abrasives is about 92 g./m. at an average weight per unit area of 335 g./m.'. The support fabric of type X for abrasives is EXAMPLE 6 A warp yarn of native cotton of count number 20 which had before spinning, in the flock form, been boiled with alkali, washed and rinsed, is core-sized in a sizing trough with a formulation consisting of:

70 parts by weight of oxidatively degraded starch;

4 parts by weight of cocoanut fat alcohol polyglycol ether having 12 ethylene oxide molecules per fatty alcohol; and

926 parts by weight of water; and dried on an air drying machine at 130 C., the size content being percent of absolutely dry material, and subsequently woven with an unsized weft yarn of count number 28 to give an X-grey fabric for abrasives (twill, warp 34 ends/cm., weft 20.5 picks/cm.). The grey fabric for abrasives manufactured in this way is, without desizing, impregnated with a finish consisting of:

60 parts by weight ofanimal hide glue (300 bl. gr. 100 mp.);

50 parts by weight of a copolymeric aqueous acrylate dispersion of 35 percent by weight of ethyl acrylate, 10 percent by weight of methacrylic acid, 40 percent by weight of methyl methacrylate and percent by weight of acrylamide;

30 parts by weight of kaolin;

1 part by weight of naphthalenesulphonate; and

859 parts by weight of water; and dried at 145 C. with simultaneous stretching; giving a sideways contraction of about 12 percent, and set. The content of finish in the X-support fabric for abrasives is about 90 g./m. at an average weight per unit area of 335 g./m.hu 2. The X-support fabric for abrasives is treated by coating it on the particle side with a composition, as in example 3, and as in the continuation of the example and is processed into an abrasive fabric.

EXAMPLE 7 A cotton warp yarn of count number 34 which before spinning had, in the flock form, been boiled with alkali, washed and rinsed, is sized in a sizing trough with a liquor consisting of:

100 parts by weight of reactive copolymeric aqueous acrylate dispersion, 45 percent by weight of ethyl acrylate, 35 percent by weight of butyl acrylate, 10 percent by weight of vinyl acetate and 10 percent by weight of N- methylolacrylamide;

5 parts by weight of water-soluble copolymer of 30 percent by weight of acrylic acid and 70 percent by weight of butyl acrylate;

five parts by weight of oleyl alcohol polyglycol ether having eight molecules of ethylene oxide per fatty alcohol; and

890 parts by weight of water; and subsequently dried in an air tunnel at C. and set. The size content is 10 percent of absolutely dry material. After weaving with an unsized weft yarn of the same composition, the J-grey fabric for abrasives (twill, warp 38 ends/cm, weft 26.5 picks/cm.) is, without desizing, immediately impregnated with a finishing solution consisting of:

100 parts by weight of reactive copolymeric aqueous acrylate dispersion, 10 percent by weight of ethyl acrylate, 35 percent by weight of butyl acrylate, 10 percent by weight of vinyl acetate and 10 percent by weight of N- methylolacrylamide;

5 parts by weight of a water-soluble copolymer of 30 percent by weight of acrylic acid and 70 percent by weight of butyl acrylate;

20 parts by weight of methylene chloride;

30 parts by weight of kaolin;

20 parts by weight of dimethylolglyoxalmonourein;

2 parts by weight of magnesium chloride; and

823 parts by weight of water;

and dried at C. while stretching it, in the course of which the fabric contracts by 10 percent in width, and set. The content of finish in the J-support fabric for abrasives is 85 g./m. at an average weight per unit area of 275 gm. The .l-fabric is further processed to give a water-resistant abrasive fabric with phenolic resin bonding of the particles, by coating the support fabric for abrasives with a composition according to the invention as described in example 3 to serve as the intermediate layer and subsequently treating it as described in more detail in the example.

EXAMPLE 8 A warp yarn of 60 percent by weight of regenerated cellulose (polynosic type) or a cotton fiber material which had be fore spinning, for example, in the flock form, been boiled with alkali, washed and rinsed, and 40 percent by weight of polyamide-6,6 fiber of count number 34 is sized in a sizing trough with a liquor consisting of:

20 parts by weight of water-soluble copolymer of 30 percent by weight of acrylic acid and 70 percent by weight of butyl acrylate;

70 parts by weight of reactive copolymeric aqueous acrylate dispersion, 45 percent by weight of ethyl acrylate, 30 percent by weight of butyl acrylate and 25 percent by weight of N-methylolacrylamide;

10 parts by weight of urea;

3 parts by weight of oleyl alcohol polyglycol ether having 15 ethylene oxide groups per molecule of fatty alcohol; and

897 parts by weight of water; and subsequently dried in an air tunnel at 145 C. and set. The size content is 8 percent of absolutely dry material. After weaving with unsized yarn of the same composition the J-grey fabric for abrasives (twill, warp 38 ends/cm, weft 26.5 picks/cm.) is, without desizing, immediately impregnated with a finishing solution consisting of:

30 parts by weight ofanimal hide glue (300 bl. gr. 100 mp.

100 parts by weight of reactive copolymeric aqueous acrylate dispersion of 45 percent by weight of ethyl acrylate, 5 percent by weight of N-methylolacrylamide and 50 percent by weight of vinyl acetate;

30 parts by weight of kaolin;

3 parts by weight of methylene chloride; and

827 parts by weight of water; and dried at C. with simultaneous stretching, with a sideways contraction of 11 percent at 175 C., and set. The content of finish in the .l-support fabric for abrasives is 80 g,/m.. at an average weight per unit area of 270 gJmF. The .lfabric is provided with an intermediate layer on the particle side, using a composition according to the invention from example 1 and is finally worked into an abrasive fabric as described in the example.

EXAMPLE 9 A warp yarn of count number of 70 percent by weight of native cellulose, which had been boiled with alkali and washed in the flock form, and percent by weight of polyacrylonitrile fiber is core-sized in a sizing trough using a formulation consisting of:

50 parts by weight of starch digested by acid degradation;

3 parts by weight of cocoanut fat alcohol polyglycol ether having eight ethylene oxide groups per molecule;

on a belt grinding machine and tested in a test grinding procedure. In this test grinding procedure an abrasive fabric manufactured according to the invention was compared with a support fabric for abrasives which had been sized conventionally, subsequently not desized and thereafter conventionally finished, in respect of the technical aspects of the test grinding. A specified iron pipe was ground at constant pressure load. Furthermore, the surface of the abrasive fabric was assessed visually as regards abrasion and breaking off of particles after the test grinding process. The yardstick was in each case the duration of grinding achieved until the abrasive particles broke off completely. Furthermore, the adhesion of the abrasive fabric finish was tested by applying an intermediate layer according to the invention and laminating this sample to sheet metal by means of the phenolic resin primer binder. The sample was cured and after having been climatically treated the peel strength as well as the point of peeling was determined.

vention, with size, finish and impregnation according to the invention and composition according to the lllVtllLlOll as intermediate layer.

woven with unsized yarn material of count number 28 to give an X-grey fabric for abrasives (twill, warp 34 ends/cm, weft 20.5 picks/cm). The X-grey fabric for abrasives manufactured in this way is, without desizing, impregnated with a finish consisting of:

50 parts by weight of kaolin;

30 parts by weight of a water-soluble copolymer of 30 percent by weight of acrylic acid and 70 percent by weight of butyl acrylate;

100 parts by weight of a copolymeric aqueous acrylate dispersion of 45 percent by weight of ethyl acrylate, 35 percent by weight of butyl acrylate, 10 percent by weight of vinyl acetate and l0 percent by weight of N- methylolacrylamide;

5 parts by weight of toluene; and

815 parts by weight of water; and dried at 145 C. with stretching, in the course of which the fabric contracts by 12 percent in width, and set. The content of. in the X-fabric is 90 g./m. The X-support fabric for abrasives is provided with an intermediate layer using a composition according to the invention and according to example 2, and is further processed into the finished abrasive fabric as described in the example.

The abrasive fabrics obtained according to examples 49 are tested to demonstrate the advance over the prior art.

The abrasive fabric strip obtained shows a good bond, good flexibility, good wet strength and good adhesion of the finish to the nondesized fabric.

In order to test the adhesion achieved, the previously prepared support fabric for abrasives was primed with phenolic resin, using the composition according to the invention as an intermediate layer on the particle side, and abrasive (electrocorundum or silicon carbide) of particle size number subsequently applied electrostatically, and the material was predried or precured as a festoon. Thereafter the second covering binder layer was applied using a phenolic resin binder with appropriate additions of fillers and dyestuffs and the entire system was again dried as a festoon and subsequently cured. After the curing process, the support fabric for abrasives was climatically treated in a moist air atmosphere in order to restore its hygroscopic equilibrium and was then wound up.

Thereafter the abrasive fabric manufactured in this way was subjected to a mechanical breaking process, described as flexing in the technology of abrasive fabric manufacture, and was processed into abrasive fabric strips. These were clamped The tests shown that the fabric web for supporting abrasive particles, according to the present invention, is in several respects surprisingly improved.

The present invention also relates to a finishing agent which is intended for finishing the core-sized warp yarn and the unsized weft yarn for the manufacture of fabric webs for supporting abrasive particles and which is characterized in that this contains, in an aqueous medium, organic solvents and swelling agents which at temperatures of l5-45 C, are a swelling agent and at 65200 C. are a solvent for the entire size present on the warp yarn, or for a part thereof, and with the finishing agent being a binder combination having the composition described in the preferred embodiment, as disclosed after the test of example 3, the use of which is explained in more detail in the examples which follow.

EXAMPLE 10 A yarn material sized and woven as in example 6 is impregnated as follows:

120 parts by weight of copolymeric aqueous acrylate dispersion of 75 percent by weight of ethyl acrylate, 15 percent by weight of acrylonitrile and 10 percent by weight of N- methylolacrylamide;

10 parts by weight of water-soluble copolymer of 30 percent by weight of acrylic acid and 70 percent by weight of butyl acrylate;

10 parts by weight of toluene;

60 parts by weight ofkaolin;

50 parts by weight of degraded starch (oxidative); and

750 parts by weight of water;

and dried at 130 C. with stretching. The content of finish is g./m. at an average weight per unit area of 335 g/m". The X- fabric is further treated as in example 5.

EXAMPLE ll A grey fabric for abrasives manufactured as in example 7 is impregnated with the following formulation:

parts by weight of acrylate dispersion (as in example 7);

10 parts by weight of methylene chloride;

20 parts by weight of cocoanut fat alcohol polyglycol ether having eight ethylene oxide molecules;

60 parts by weight of kaolin;

30 parts by weight of animal hide glue (300 bl. gr.l00 mp.);

and

780 parts by weight of water;

and dried at 145 C. with stretching and set. The content of finish was 75 g./m. at an average weight per unit area of 270 g./m. of the J-support fabric for abrasives. The J-abrasive fabric is further processed as in example 8.

EXAMPLE 12 A grey fabric for abrasives manufactured as in example 5 is impregnated with the following finish:

60 parts by weight of animal hide glue (300 bl. gr. 100 mp.

50 parts by weight of copolymeric aqueous acrylate dispersion of 35 percent by weight of ethyl acrylate, percent by weight of methacrylic acid, 40 percent by weight of methyl methacrylate and percent by weight of acrylamide;

30 parts by weight of kaolin;

30 parts by weight of cocoanut fat alcohol polyglycol ether having five ethylene oxide molecules, dissolved 1:1 in white spirit; and

830 parts by weight of water;

and dried at 145 C. while stretching and set. The content of finish is 90 g./m." at an average weight per unit area of 335 g./m The X-fabric is given its final treatment as described in example 9.

EXAMPLE 13 A grey fabric for abrasives manufactured according to example 9 is impregnated with the following finish:

lOO parts by weight of copolymeric aqueous acrylate dispersion of 45 percent by weight of ethyl acrylate, 35 percent by weight of butyl acrylate, 10 percent by weight of vinyl acetate and 10 percent by weight of N-methylolacrylamide; parts by weight of methylene chloride; 30 parts by weight of kaolin; 20 parts by weight of dimethylolglyoxalmonourein; 2 parts by weight of magnesium chloride; and 823 parts by weight of water; and dried and stretched at 145 C. in order to set it. The X- support fabric for abrasives has an average weight per unit area of 395 g./m. The X-abrasive fabric is given its final treatment as described in example 9 EXAMPLE 14 A grey fabric for abrasives manufactured according to example 6 is impregnated with the following finish:

30 parts by weight of water-soluble copolymer of 30 percent by weight of acrylic acid, and 70 percent by weight of butyl acrylate;

I00 parts by weight of copolymeric aqueous acrylate dispersion of 45 percent by weight of ethyl acrylate, 35 percent by weight of butyl acrylate, 10 percent by weight of vinyl acetate and 10 percent by weight of N-rnethylolacrylamide;

I00 parts by weight of cocoanut fat alcohol polyglycol ether with eight ethylene oxide groups per molecule; and

810 parts by weight of water; dried at 145 C. with stretching, and set. The X-support fabric for abrasives has a content of finish of90 g./m. at an average weight per unit area of 335 g./m. and is further processed to give an abrasive fabric as described in example 6.

FIG. 6 shows: at A, the core-sized and finished warp yarn A without interfacial layer and the finished weft yarn B. This is a constituent of FIGS. 1-5 with the fabric web for supporting abrasive particles, shown in FIG. I.

The fabrics listed in the Table which follows are for example additionally suitable as grey fabrics for abrasives, for the manufacture of support fabrics for abrasive particles.

A particularly advantageous abrasive fabric web is, by a combination of the coating according to the invention, achieved especially for wet grinding if one uses a finish and a reverse side sealer layer of the reacted mixtures of components (a), (b), (c) and (d) ofthe Abstract.

TEXTILE TECHNICAL DATA ON GREY FABRICS FOR ABRASIVES According to the present invention, abrasive fabric webs are obtained which are extensively flexible and the effectiveness of which from the point of view of grinding technology also remains fully preserved under the prolonged influence of water, so that the webs are far superior to earlier products.

Suitable support fabrics are all the fabrics described, such as, for example, regenerated and native cellulose or synthetic fibers. The manufacture of the new abrasive fabric webs for wet grinding grades is explained in the following examples.

EXAMPLE 15 170 parts by weight of epoxide resin based on Bisphenol A,

having an epoxide equivalent weight of 185-195, viscosity in cP at 25 C. 10,000-15,000;

30 parts by weight of epoxide resin based on Bisphenol A,

internally plasticized by reaction with castor oil;

3.0 parts by weight of carbamic acid ethyl ester;

27.5 parts by weight of metaphenylenediamine; and

900 parts by weight of solvent (xylene and methyl isobutyl ketone in the ratio of 80:20). The further processing is described after example 20.

EXAMPLE 16 190 parts by weight of epoxide resin based on Bisphenol A having an epoxide equivalent weight of 185-195, viscosity in cP at 25 C. 10,000-15,000;

10 parts by weight of epoxide resin based on Bisphenol A which is internally plasticized by reaction with castor oil;

10 parts by weight of carbamic acid ethyl ester;

54 parts by weight of 4,4-diaminodiphenylmethane; and

1,200 parts by weight of solvent (xylene and methyl isobutyl ketone in the ratio of 80:20). The further processing is described after example 20.

EXAMPLE 1? 180 parts by weight of epoxide resin based on Bisphenol A having an epoxide equivalent weight of 185-195, viscosity in c? at 25 C. 10,000-15,000;

20 parts by weight of epoxide resin based on Bisphenol A which is internally plasticized by reaction with castor oil;

20 parts by weight of carbamic acid ethyl ester;

67 parts by weight of diaminodiphenylsulphone; and

1,100 parts by weight of solvent (xylene and methyl isobutyl ketone in the ratio of 80:20). The further processing is described after example 20.

EXAMPLE 18 EXAMPLE 19 190 parts by weight of liquid epoxide resin based on Bisphenol A having an epoxide equivalent weight of 185-195, viscosity in c? at 25 C. 10,000-15,000;

10 parts by weight of epoxide resin based on Bisphenol A internally plasticized by reaction with castor oil;

2 parts by weight of carbamic acid ethyl ester;

54 parts by weight of 4,4'-diaminodiphenylmethane;

100 parts by weight of kaolin; and

20 parts by weight of solvent (xylene, methyl isobutyl ketone in the ratio of 80:20).

The further processing is described after example 20.

EXAMPLE 20 180 parts by weight of liquid epoxide resin based on Bisphenol A having an epoxide equivalent weight of 185-195, viscosity in c? 25C. 10,000-15,000;

20 parts by weight of epoxide resin based on Bisphenol A internally plasticized by reaction with castor oil;

2 parts by weight of carbamic acid ethyl ester;

67 parts by weight of diaminodiphenylsulphone; 100 parts by weight of kaolin; and 20 parts by weight of solvent (xylene and methyl isobutyl ketone in the ratio of :20).

Examples of the manufacture of the abrasive fabric webs according to the invention, using the new compositions of examples 15-20 as a finish and using a reverse side sealing coat were prepared as follows:

A desized, bucked, washed and dyed cotton twill fabric having a grey fabric weight of 200 g./m. for example, serves as the starting fabric web.

It is impregnated in a full bath with a finish described in accordance with the invention and according to examples 15 to 17, and subsequently squeezed out to the extent that an application of finishing agent solution of about percent relative to grey weight remains in the fabric. Thereafter this finish fabric web is physically dried on a stenter frame or a cylinder drying machine. In the course of this, the fabric must be stretched lengthwise in such a way as to contract about 12 percent in width. As a result of this mechanical stretching process the longitudinal extension caused by the construction of the fabric, which is undesirable when using the abrasive fabric web, is restricted to a minimum. The drying on the stenter frame or the cylinder drying machine is appropriately effected at temperatures of about 70 to 80 C. The reverse side of the fabrics is given a sealer coat in one or more further process stages, using a coating composition containing fillers, described according to the invention, and according to examples 18 to 20 and the fabric is again dried at a temperature of about 70 to 80 C. The side facing the abrasive particles is optionally coated with the composition according to the invention devoid of fillers (compare FIGS. 1 to 5, number 2 with the coating devoid of fillers according to the invention).

The fabrics which have been finished according to the invention in this way can in the usual manner be provided with abrasive particles utilizing phenolic resins as the binder. v

Description of the further process stages for the manufacture of abrasive fabric webs for wet grinding.

A liquid phenol-formaldehyde condensation product having a viscosity of 8,000 to 10,000 cl at 20 C. and a B-time (cure time until the phenolic resin changes to the so-called B-state) of about 12 minutes at C. is applied in an amount of 120 g./m.. Silicon carbide of particle size number 50 is scattered into this phenolic resin binder layer which is still moist.

The precure 0f the primer binder is now taken beyond the B-point to the stage that the abrasive particles are well fixed to the surface of the support, so that on application of the covering binder it can no longer break offfrom the primer binder.

A mixture of:

60 percent by weight of a liquid phenol-formaldehyde condensation product having a viscosity of 1000 cf; and

40 percent by weight of inorganic fillers is used as the covering binder.

This binder is applied by the roller application process in an amount of 250 to 300 g./m. The cure is effected over the course of 6 hours with a curve of the temperature course which has been empirically determined to be the optimum.

After the curing process, the abrasive article which has necessarily been dried out during the cure is returned to its hygroscopic equilibrium under normal climatic conditions by moistening it with steam.

The abrasive fabric webs finished according to the invention with the compositions according to examples 15 to 17 which have subsequently been provided with a sealer coat on the reverse side of the fabric using the compositions according to examples 18 to 20 are distinguished by the following advantages in comparison with the abrasive fabric webs manufactured with the usual finishes and coating compositions:

They are extensively flexible and their effectiveness from the point of view of grinding technology remains fully preserved even under the prolonged inflluence ofwater.

The preceding exam les can be repeated with similar success by substituting the generically and. specifically described reactants and operating conditions of this invention for those used in the preceding examples,

From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing form the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Consequently, such changes and modifications are properly, equitably, and intended to be, within the full range of equivalence of the following claims.

We claim:

1. In a coated abrasive article comprising a finished grey fabric support, an elastic sealing intermediate layer, abrasive particles distributed thereon and a phenol aldehyde resin binder layer for the abrasive particles, the improvement whereby said intermediate layer comprises:

a. an epoxide resin based on 4,4'-dihydroxy-diphenyl-2,2-

propane;

b. an epoxide resin based on 4,4'-dihydroxy-diphenyl-2,2-

propane internally plasticized by reaction with castor oil;

c. a carbamic acid alkyl ester; and

d. an epoxide resin curing agent.

2. The coated abrasive article of claim 1, wherein component (a) is about 10-90 parts by weight, component (c) is about 0.5 to 80 parts by weight.

3. The coated abrasive article of claim 1, wherein component (a) is about 80-95 parts by weight, component (b) is about 20-5 parts by weight, and component (c) is about 0.5 to 40 parts by weight 4. The coated abrasive article of claim 1, wherein the finished grey fabric support has a warp yarn and a weft yarn.

The coated abrasive article of claim 4, wherein said abrasive fabric consists essentially of woven fibers selected from the group consisting of cotton, regenerated cellulose, regenerated cellulose of the polynosic fiber type, polyester fibers, polyamide fibers and admixtures thereof, and said.

fibers pretreated whereby they are freed of the antiadhesive constituents by one or more alkaline washing and rinsing processes.

6. The coated abrasive article of claim 4, wherein the warp yarn contains a size having the composition comprising:

30 to 90 parts by weight ofa starch selected from the group consisting of corn starch, rice starch and potato starch digested by acid degradation;

3 to 20 parts by weight of a fatty alcohol polyglycol ether;

to 50 parts by weight of a copolymeric aqueous acrylate dispersion of 35 percent by weight of ethyl acrylate, l0 percent by weight of methacrylic acid, 40 percent by weight of methyl methacrylate and percent by weight of acrylamide; and

957 to 840 parts by weight of water.

7. The coated abrasive article of claim 6, wherein the warp yarn is core sized with said size.

8. The coated abrasive article of claim 7, wherein the size present on the warp yarn contains, emulsified in the aqueous medium, an emulsified organic solvent which at temperatures of 15-45 C. is a swelling agent and from above to 200 C. is a solvent for the size present on the warp yarn.

9. The coated abrasive article of claim 4, wherein the warp yarn has a size having the composition comprising:

1 to 25 parts by weight of water-soluble copolymer of 30 percent by weight of acrylic acid, percent by weight of butyl acrylate;

3 to 15 parts by weight of cocoanut fat alcohol polyglycol ether having 5-12 ethylene oxide groups per fat molecule;

10 to parts by weight of copolymeric aqueous acrylate dispersion of 45 percent by weight of ethyl acrylate, 35 percent by weight of butyl acrylate, 10 percent by weight of vinyl acetate and 10 percent by weight of N- methylolacrylamide; and

986 to 870 parts by weight ofwater.

IG'TEe coated abrasive product of claim I, mre in the weft yarn contains a finish having a composition comprising:

10 to parts by weight of animal hide glue;

80 to 30 parts by weight of a copolymeric aqueous acrylate dispersion of 35 percent by weight of 20 percent by weight of ethyl acrylate, 5 to 25 percent by weight of methacrylic acid, 0 to 40 percent by weight of methyl methacrylate, 5 to 25 percent by weight of acrylonitrile, 0 to 45 percent by weight of butyl acrylate and 5 to 15 percent by weight of N-methylolacrylamide;

5 to 10 percent by weight of cocoanut fat alcohol polyglycol ether having five to 12 ethylene oxide groups per molecule of fatty alcohol;

1 to 35 parts by weight of chlorinated hydrocarbon; and

785 to 864 parts by weight of water.

11. The coated abrasive article according to claim 4, wherein the weft yarn has a finish having a composition comprising:

50 to parts by weight of an aqueous copolymeric acrylate dispersion of 45 to 20 percent by weight of ethyl acrylate, 5 to 25 percent by weight of methacrylic acid, 0 to 40 percent by weight of methyl methacrylate, S to 25 percent by weight of acrylonitrile, 0 to 45 percent by weight of butyl acrylate and 5 to 15 percent by weight of N-methylolacrylamide;

3 to 20 parts by weight of water-soluble copolymer of 30 percent by weight of acrylic acid and 70 percent by weight of butyl acrylate;

5 to 40 parts by weight of dimethylolgly-oxalmonourein;

l to 5 parts by weight of magnesium chloride;

1 to 30 parts by weight of toluene;

755 to 940 parts by weight of water.

12. The coated abrasive article of claim I, wherein said finished fabric support has a reverse side sealing layer having the composition of said intermediate layer.

* k k i 

2. The coated abrasive article of claim 1, wherein component (a) is about 10-90 parts by weight, component (c) is about 0.5 to 80 parts by weight.
 3. The coated abrasive article of claim 1, wherein component (a) is about 80-95 parts by weight, component (b) is about 20-5 parts by weight, and component (c) is about 0.5 to 40 parts by weight.
 4. The coated abrasive article of claim 1, wherein the finished grey fabric support has a warp yarn and a weft yarn.
 5. The coated abrasive article of claim 4, wherein said abrasive fabric consists essentially of woven fibers selected from the group consisting of cotton, regenerated cellulose, regenerated cellulose of the polynosic fiber type, polyester fibers, polyamide fibers and admixtures thereof, and said fibers pretreated whereby they are freed of the antiadhesive constituents by one or more alkaline washing and rinsing processes.
 6. The coated abrasive article of claim 4, wherein the warp yarn contains a size having the composition comprising: 30 to 90 parts by weight of a starch selected from the group consisting of corn starch, rice starch and potato starch digested by acid degradation; 3 to 20 parts by weight of a fatty alcohol polyglycol ether; 10 to 50 parts by weight of a copolymeric aqueous acrylate dispersion of 35 percent by weight of ethyl acrylate, 10 percent by weight of methacrylic acid, 40 percent by weight of methyl methacrylate and 15 percent by weight of acrylamide; and 957 to 840 parts by weight of water.
 7. The coated abrasive article of claim 6, wherein the warp yarn is core sized with said size.
 8. The coated abrasiVe article of claim 7, wherein the size present on the warp yarn contains, emulsified in the aqueous medium, an emulsified organic solvent which at temperatures of 15*-45* C. is a swelling agent and from above 65* to 200* C. is a solvent for the size present on the warp yarn.
 9. The coated abrasive article of claim 4, wherein the warp yarn has a size having the composition comprising: 1 to 25 parts by weight of water-soluble copolymer of 30 percent by weight of acrylic acid, 70 percent by weight of butyl acrylate; 3 to 15 parts by weight of cocoanut fat alcohol polyglycol ether having 5-12 ethylene oxide groups per fat molecule; 10 to 80 parts by weight of copolymeric aqueous acrylate dispersion of 45 percent by weight of ethyl acrylate, 35 percent by weight of butyl acrylate, 10 percent by weight of vinyl acetate and 10 percent by weight of N-methylolacrylamide; and 986 to 870 parts by weight of water. 10 The coated abrasive product of claim 4, wherein the weft yarn contains a finish having a composition comprising: 10 to 100 parts by weight of animal hide glue; 80 to 30 parts by weight of a copolymeric aqueous acrylate dispersion of 35 percent by weight of 20 percent by weight of ethyl acrylate, 5 to 25 percent by weight of methacrylic acid, 0 to 40 percent by weight of methyl methacrylate, 5 to 25 percent by weight of acrylonitrile, 0 to 45 percent by weight of butyl acrylate and 5 to 15 percent by weight of N-methylolacrylamide; 5 to 10 percent by weight of cocoanut fat alcohol polyglycol ether having five to 12 ethylene oxide groups per molecule of fatty alcohol; 1 to 35 parts by weight of chlorinated hydrocarbon; and 785 to 864 parts by weight of water.
 11. The coated abrasive article according to claim 4, wherein the weft yarn has a finish having a composition comprising: 50 to 150 parts by weight of an aqueous copolymeric acrylate dispersion of 45 to 20 percent by weight of ethyl acrylate, 5 to 25 percent by weight of methacrylic acid, 0 to 40 percent by weight of methyl methacrylate, 5 to 25 percent by weight of acrylonitrile, 0 to 45 percent by weight of butyl acrylate and 5 to 15 percent by weight of N-methylolacrylamide; 3 to 20 parts by weight of water-soluble copolymer of 30 percent by weight of acrylic acid and 70 percent by weight of butyl acrylate; 5 to 40 parts by weight of dimethylolgly-oxalmonourein; 1 to 5 parts by weight of magnesium chloride; 1 to 30 parts by weight of toluene; 755 to 940 parts by weight of water.
 12. The coated abrasive article of claim 1, wherein said finished fabric support has a reverse side sealing layer having the composition of said intermediate layer. 